Unleashing the power of AI to track animal behavior

Movement offers a window into how the brain operates and controls the body. From clipboard-and-pen observation to modern artificial intelligence-based techniques, tracking human and animal movement has come a long way. Current ...

A new technique to detect invisibility cloaks

A study developed by researchers from the Universitat Politècnica de València (UPV), associated with the Nanophotonics Technology Center (NTC) and the company DAS Photonics, promises to revolutionize the design of so-called ...

Acoustics researchers develop novel underwater carpet cloak

Acoustic camouflage, realized by controlling wave propagation, has attracted much attention in recent years. Aided by a reflecting surface, acoustic carpet cloak has become one of the most practically feasible invisibility ...

Physicists embark on a hunt for a long-sought quantum glow

For "Star Wars" fans, the streaking stars seen from the cockpit of the Millennium Falcon as it jumps to hyperspace is a canonical image. But what would a pilot actually see if she could accelerate in an instant through the ...

Making an object invisible under fluid flow

The invisibility cloak is an artifact that can make the wearer transparent, rendering it undetectable to observers outside. Perhaps, one of the most well-known examples is the invisibility cloak possessed by Harry Potter ...

Bending light for safer driving; invisibility cloaks to come?

Optical cloaking allows objects to be hidden in plain sight or to become invisible by guiding light around anything placed inside the cloak. While cloaking has been popularized in fiction, like in the "Harry Potter" books, ...

How to thermally cloak an object

Can you feel the heat? To a thermal camera, which measures infrared radiation, the heat that we can feel is visible, like the heat of a traveler in an airport with a fever or the cold of a leaky window or door in the winter.

page 1 from 13

Invisibility

Invisibility is the state of an object that cannot be seen. An object in this state is said to be invisible (literally, "not visible"). The term is usually used as a fantasy/science fiction term, where objects are literally made unseeable by magical or technological means; however, its effects can also be seen in the real world, particularly in physics and perceptional psychology.

Since objects can be seen by light in the visible spectrum from a source reflecting off their surfaces and hitting the viewer's eye, the most natural form of invisibility (whether real or fictional) is an object that neither reflects nor absorbs light (that is, it allows light to pass through it). In nature, this is known as transparency, and is seen in many naturally occurring materials (although no naturally occurring material is 100% transparent).

Visibility also depends on the eyes of the observer and/or the instruments used. Thus an object can be classified as "invisible to" a person, animal, instrument, etc. In the research of sensorial perception invisibility has been shown to happen in cycles.

Invisibility is often considered the supreme form of camouflage, as it doesn't show any kind of vital, visual, nor any of the frequencies of the electromagnetic spectrum such as radio, infrared, ultra violet, etc.

This text uses material from Wikipedia, licensed under CC BY-SA